Tape cassette, in particular a magnetic tape cassette, and a reel support liner therefor

Abstract

In a tape cassette possessing symmetrically arranged support liners, a compressive force dependent on the tape roll diameter is exerted by the liner and utilized for centering the roll and the tape. Force/diameter relationships, and embodiments of folded liners for achieving individual forces are described. A novel dynamic liner arrangement can be used in any tape cassette possessing high winding speeds and sensitive tapes, with frequently alternating rewind/playback operation.

We claim: 
     
       1. A tape cassette, in particular a magnetic tape cassette, comprising a cassette housing having top and bottom walls and front and back walls and at least one flangeless reel contained therein, said reel having an external diameter, and onto which reel the magnetic tape is wound into a tape roll and/or from which it is unwound, and at least two substantially rectangular liners being provided one on each side of the reel of wound tape between the latter and the top and bottom walls, respectively, said liners comprising peripheral bent-over liner portions which are bent over at an angle to and in a direction toward the central plane of the cassette and which exert a resilient pressure on the tape roll(s), said bent-over liner portions consisting in a back liner portion exerting a resilient pressure on a tape roll region facing the back wall of the cassette and a front liner portion exerting a resilient pressure on a tape roll region near the front wall of the cassette, wherein each of the liners has at least two substantially longitudinal folds which limit said back and front bent-over liner portions, said folds being arranged at a distance equal to or smaller than the external diameter of the reel and intended for contacting the inner surfaces of said top and bottom walls of the cassette, and the two folds limit a middle part between them, and wherein by said liners bearing with said folds, arranged at said distance from one another, against the respective inner surface of the top and bottom walls, and   by said peripheral liner portions bent over at a certain angle towards the central plane of the cassette and exerting said resilient pressure on the tape roll,   a bending force is produced on said middle part of each liner which as a result arches towards said reel(s) and exerts a pressure force thereon, which pressure force has a minimum value when acting on an empty reel and a maximum value when acting on a reel carrying a full tape roll.   
     
     
       2. A cassette as claimed in claim 1, wherein the back bent-over liner portion is formed by a continuous longitudinal fold extending as far as the narrow sides of the liner. 
     
     
       3. A cassette as claimed in claim 1, wherein the front area of the liner is formed by at least one fold which extends essentially in the longitudinal direction of the liner, ends before the run-in and run-out area of the tape at the tape roll and causes the run-in and run-out area of the liner to curve. 
     
     
       4. A cassette as claimed in claim 1, wherein the pressure force exerted on the reel increases continuously from the minimum value to the maximum value. 
     
     
       5. A cassette as claimed in claim 1, wherein the minimum value of the pressure force is from about 1 to about 4 cN, and the maximum value is from about 7 to 15 cN. 
     
     
       6. A cassette as claimed in claim 5, wherein the minimum value is about 2 cN and the maximum value about 10 cN. 
     
     
       7. A cassette as claimed in claim 1, wherein the gradient of the pressure force as a function of the instantaneous tape roll diameter is from about 0.1 to about 0.3 cN/mm, and decreases from about 0.3 cN/mm in the region of the minimum pressure force to about 0.1 cN/mm in the region of the maximum pressure force. 
     
     
       8. A cassette as claimed in claim 1, wherein the gradient of the compressive force as a function of the instantaneous tape roll diameter decreases from about 0.3 cN/mm in the region of the minimum pressure force to about 0.1 cN/mm in the region of the maximum pressure force. 
     
     
       9. A cassette as claimed in claim 1, wherein a 50 μm thick polyester film is folded through an angle of about 8°-30° toward the central plane of the cassette. 
     
     
       10. A cassette as claimed in claim 9, wherein a 50 μm thick polyester film is folded through an angle of about 10°-25° toward the central plane of the cassette. 
     
     
       11. A cassette as claimed in claim 1, wherein the front bent-over liner portion is folded through about 13°-20° and the back bent-over liner portion through about 20°, the angles being relative to the central plane of the cassette. 
     
     
       12. A cassette as claimed in claim 1, wherein the distance of the longitudinal fold for the front bent-over liner portion from the front edge of the liner is smaller than the distance of the longitudinal fold for the back bent-over liner portion from the back edge of the liner. 
     
     
       13. A cassette as claimed in claim 1, wherein the liner possesses, in the run-in and run-out area, cutouts through which the tape passes in the region of the periphery of the tape roll. 
     
     
       14. A cassette as claimed in claim 1, wherein tape guide elements which guide the tape to or from the periphery of the tape roll are provided in the run-in and run-out area of the tape. 
     
     
       15. A tape cassette, in particular a magnetic tape cassette, comprising a cassette housing having top and bottom walls and front and back walls and at least one flangeless reel contained therein, said reel having an external diameter, and onto which reel the magnetic tape is wound into a tape roll and/or from which it is unwound, and at least two substantially rectangular liners being provided one on each side of the reel of wound tape between the latter and the top and bottom walls, respectively, said liners comprising peripheral bent-over liner portions which are bent over at an angle to and in a direction toward the central plane of the cassette and which exert a resilient pressure on the tape roll(s), said bent-over liner portions consisting in a back liner portion exerting a resilient pressure on a tape roll region facing the back wall of the cassette and a front liner portion exerting a resilient pressure on a tape roll region near the front wall of the cassette, wherein each of the liners has at least two substantially longitudinal folds which limit said back and front bent-over liner portions, said folds being arranged at a distance equal to or smaller than the external diameter of the reel and intended for contacting the inner surfaces of said top and bottom walls of the cassette, and the two folds limit a middle part between them, and wherein   by said liners bearing with said folds, arranged at said distance from one another, against the respective inner surface of the top and bottom walls, and   by said peripheral liner portions bent over at an angle in the range from about 10° to about 25° towards the central plane of the cassette and exerting said resilient pressure on the tape roll,   a bending force is produced on said middle part of each liner which as a result arches towards said reel(s) and exerts a pressure force thereon in the range from about 2 cN to about 10 cN, which pressure force has a minimum value of about 2 cN when acting on an empty reel and a maximum value of about 10 cN when acting on a reel carrying a full tape roll.   
     
     
       16. A tape cassette, in particular a magnetic tape cassette, comprising a cassette housing having top and bottom walls and front and back walls and at least one flangeless reel contained therein, said reel having an external diameter, and onto which reel the magnetic tape is wound into a tape roll and/or from which it is unwound, and at least two substantially rectangular liners being provided one on each side of the reel of wound tape between the latter and the top and bottom walls, respectively, said liners comprising peripheral bent-over liner portions which are bent over at an angle to and in a direction toward the central plane of the cassette and which exert a resilient pressure on the tape roll(s), said bent-over liner portions consisting in a back liner portion exerting a resilient pressure on a tape roll region facing the back wall of the cassette and a front liner portion exerting a resilient pressure on a tape roll region near the front wall of the cassette, wherein each of the liners has at least two folds which limit said back and front bent-over liner portions, said folds being arranged at a distance equal to or smaller than the external diameter of the reel and intended for contacting the inner surfaces of said top and bottom walls of the cassette, and the two folds limit a middle part between them, and wherein   by said liners bearing with said folds, arranged at said distance from one another, against the respective inner surface of the top and bottom walls, and   by said peripheral liner portions bent over at an angle in the range from about 10° to about 25° towards the central plane of the cassette and exerting said resilient pressure on the tape roll,   a bending force is produced on said middle part of each liner which as a result arches towards said reel(s) and exerts a pressure force thereon, the gradient of which pressure force as a function of the instantaneous tape roll diameter decreasing from about 0.3 cN/mm, when the pressure force acts on an empty reel, to about 0.1 cN/m, when the pressure force acts on a reel carrying a full tape roll.   
     
     
       17. A liner with a substantially rectangular shape for a tape cassette as claimed in claim 1, having bent-over liner portions which comprise a back bent-over liner portion at the back wall of the cassette and a front bent-over liner portion at the front wall of the cassette, wherein the liner possesses, in the central region, two longitudinal folds which are separated by a distance equal to or smaller than the external diameter of the reel of the cassette and are intended to bear against the inner surfaces of the bottom and top wall of the cassette and between which a relatively flat middle part is provided, and the back and front bent-over portions of the liner are folded through an angle of from about 10° to about 25° with respect to the relatively flat middle part, so that the liner exerts pressure forces of from about 2 to about 10 cN on the periphery of the empty hub or on the tape roll. 
     
     
       18. A cassette as claimed in claim 5, wherein a 50 μm thick polyester film is folded through an angle of about 8°-30° toward the central plane of the cassette.